EXPANDING LESIONS of the TEMPORAL FOSSA by LESLIE OLIVER, M.B.(Lond.), F.R.C.S., F.A.C.S

Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from 546

EXPANDING LESIONS OF THE TEMPORAL FOSSA By LESLIE OLIVER, M.B.(Lond.), F.R.C.S., F.A.C.S. Neurosurgeon: Charing Cross Group of Hospitals, Royal Northern Hospital, West End Hospital for Neurology and Neurosurgery, The French Hospital, London; and Southend General Hospital, Southend-on-Sea. Senior Neurosurgeon: North-East Regional Neurological and Neurosurgical Centre, Oldchurch Hospital, Romford, Essex

Brain-stem Compression :ii.ii$iiliiiri; Expanding lesions in the temporal fossa readily ::I:. :: displace the brain-stem towards the opposite side iii.,iiiiiaiirl;illji.:;' .s.%.;.;.iig9l;;;"a.:·ii' where it is forced against the edge ofthe tentorium. ::·:: :1;·:: At the same time a wedge formed by the uncus and hippocampalgyrus is forced downward between the midbrain and the of the tentorium on the edge :i I.sapr .e side of the lesion (Fig. i). These two mechanisms produce the various stages of midbrain compression. The downward herniation of the uncus and hippocampal gyrus also compresses the homolateral oculomotor nerve. the ncrve is at copyright. Rarely :ig first stimulated and therefore the is con- pupil ::i:' but as on the nerve Y..i Lii stricted, pressure increases :!:. paralysis ensues and the pupil becomes dilated. ic?·i Usually, however, the pupil dilates as soon as the :';l..ss.l:·ii··:;.T.Rs. 't...i.li;C nerve is If the is conscious, compressed. patient :" i'lP ptosis and paralysis of the external ocular muscles ::i:;:"'··'·'!l:CiiUi%ii supplied by the oculomotor nerve may be observed. b :siai:.l:·:i·iiiiiir:::l The posterior cerebral artery prolapses through .s.".8.i.g.j.b,lSiiiiiiF·i ·:';i.ii..iiil!j.i.iii': il'.r"'e,· :ti:: the tentorial notch with the herniated brain and http://pmj.bmj.com/ a contralateral hemi- S:iliii4LtiiiiiC1;;ilii:,iii.ii :::i:' occasionally homonymous d:·*.·:1.::i i:;iiiiii.,ai:iiiii:!i:c.:·· anopia is produced by kinking of the artery or its calcarine branch over the free of the FIG. I.-Temporal lobe herniation. The groove made edge by the free edge of the tentorium on the under tentorium. surface of the left temporal lobe is indicated by Increased intracranial pressure is produced by arrows. The enlargement of the temporal lobe expansion of the lesion itself, pressure on the mid- was caused by a glioblastoma multiforme. (From brain and consequent obstruction of the aqueduct 'Basic Surgery' by kind permission of the of Sylvius, and often also by associated cerebral publishers, H. K. Lewis, London.) on October 2, 2021 by guest. Protected oedema. The increasing pressure, if not too rapid, may produce papilloedema. It also causes descent the side of the lesion, and contralateral or homo- of the brain-stem through the tentorial opening lateral hemiparesis with hypertonia, hyperreflexia sometimes resulting in sufficient traction on one or and a positive Babinski sign. (Homolateral both abducens nerves to cause unilateral or pyramidal signs are caused by displacement of the bilateral external rectus palsy. If descent of the brain-stem away from the side of the lesion and brain-stem continues, ' coning' of the cerebellar resulting indentation of the contralateral cerebral tonsils occurs at the foramen magnum and com- peduncle by the edge of the tentorium-the pression of the medulla oblongata results. Kernohan-Woltman phenomenon.) Occasionally Midbrain compression may be roughly classi- contralateral or homolateral Parkinsonian tremor fied into the following stages: and rigidity, presumably due to ischaemia of the Stage i. Clouding of consciousness, normal substantia nigra or its efferent pathways. pupils or occasionally contraction of the pupil on Stage 2. Stupor, dilatation and paralysis of the Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from October 1959 OLIVER: Expanding Lesions of the Temporal Fossa 547 pupil on the side of the lesion (Hutchinson's pupil), Personality Changes and contralateral or homolateral hemiparesis, The temporal cortex is concerned with the hypertonia, and hyperreflexia with unilateral or reception, directly or indirectly, of association- bilateral Babinski responses. Occasionally Parkin- fibre systems of the other areas of the cerebral sonian manifestations in the limbs. Increasing cortex, and may therefore be expected to play an pulse rate (the classical slow pulse, although of important part in the total function of the cerebral considerable diagnostic importance, is found less cortex. Nevertheless, personality changes are often than a fast one). rarely associated with expanding lesions of the Stage 3. Coma, dilatation and paralysis of the temporal fossa, but when they do occur they take pupil on the side of the lesion or on both sides, the form of anxiety, irritability and occasionally decerebrate rigidity with increased tendon jerks agressiveness. This is in marked contrast with and bilateral Babinski responses. Cheyne-Stokes the apathy often produced by expanding lesions respiration. Tachycardia (if cerebellar coning of the anterior fossa. is causing compression of the medulla oblongata, the pulse may be slow and associated with in- Temporal Lobe Epilepsy creased blood pressure and slow respiration). About a quarter of all cases of epilepsy have their focus of discharge in one or other temporal Stage 4. Absence of response to all external lobe. Although atrophy of part of the temporal sensory stimuli, dilatation and paralysis of both lobe is the most commonly occurring underlying pupils, flaccidity of all voluntary muscles, absent pathological process, tumours account for a sig- tendon reflexes, bilateral Babinski responses or nificant proportion of cases of temporal lobe absent plantar reflexes. Rapid weak pulse. epilepsy. Often the discharge is confined to the Shallow slow respirations. temporal lobe, giving rise to characteristic Patients may pass from one stage to another in phenomena, but it may spread over the whole of either direction. Rapidly expanding lesions in the cerebral cortex to produce grand mal attacks. the temporal fossa may lead immediately to stages There are several modes of origin of or Thus there are often no or temporal 3 4. lateralizing epilepsy and each reflects one of the functions of copyright. localizing signs with acute lesions. the temporal lobe. The commonest is a sensation in the abdomen, chest or throat (visceral Visual Field Defects aura) and is related to autonomic function. The The optic radiation sweeps widely forward in classical attack as originally described by the upper posterior part of the temporal lobe Hughlings Jackson, begins with a sensation of a before passing backward to the occipital cortex. bad smell or taste accompanied by smacking of the Thus lesions within the temporal lobe may invade lips and a ' dreamy state'; the origin of such the radiation from below, and as attacks is in the uncus, hippocampus or amygdala, optic light rays the location of olfactory and function. from above strike the lower part of the retina and gustatory http://pmj.bmj.com/ light rays from one side strike the opposite side of Other patients complain of unpleasant noises or a the retina, contralateral homonymous upper disturbance of equilibrium, sometimes so severe quadrantic field defects are produced. This is in that the patient is thrown to the ground (gyratory contrast with lesions within the parietal lobe, for epilepsy); sounds may seem unduly loud or soft; they invade the optic radiation from above and these attacks are related to the auditory and cause contralateral homonymous lower quadrantic equilibratory functions of the superior temporal field defects. A lesion arising in either situation convolution. Some patients experience sudden may eventually cut across the whole of the optic fear, anger or pleasure. There may be a sudden on October 2, 2021 by guest. Protected radiation and produce a complete contralateral feeling of familiarity with the surroundings, or the homonymous hemianopia. Involvement of the patient may feel that what is happening has taken optic radiation usually, through not invariably, place before (deja vu phenomenon). Sometimes indicates a destructive lesion within the cerebrum objects seem small and receding (micropsia), or rather than of its surface. large and near (macropsia). A vivid recollection compression of the past with its associated emotions may force its way into consciousness. Patients may carry Dysphasia out complicated acts unrelated to present events Nominal dysphasia may occur with lesions of but sometimes related to the sensory phenomena the superior temporal convolution of the dominant and tending to be aggressive (not to be confused hemisphere. Lesions which spread upwards and with post-epileptic automatism). Depersonaliza- backwards from the dominant temporal lobe may tion (a feeling of complete detachment from self), eventually cause total aphasia by destroying the and sometimes the related phenomenon of auto- speech centres of the parietal lobe. scopy (seeing an image of oneself in the external Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from 548 POSTGRADUATE MEDICAL JOURNAL October 1959 environment), are sometimes experienced. These brain damage. Sometimes, however, an acute curious effects are related to the highest functional subdural haematoma is large and clinically in- levels of the temporal lobe. distinguishable from an extradural haematoma. Its bulk tends to be in the temporal fossa although Neighbourhood Effects it extends well beyond the temporal boundaries Expansion of temporal lesions upward often and may sometimes envelop the whole hemi- causes contralateral facial paresis due to involve- sphere. Acute subdural haematomas arise from ment of the facial area of the frontal cortex or its damage to cortical vessels or venous sinuses. efferents. Expansion upwards and medially causes They have no capsule (cf. subacute and chronic contralateral facial paresis and hemiparesis by subdural haematomas). interference with the homolateral pyramidal A subacute subdural haematoma reveals itself a fibres. few weeks after a minor head injury although in many cases no history of injury is obtained. Haematomas This type of haematoma is thought to be caused Extradural Haematoma by tearing of one of the veins which pass from the cerebral cortex to the venous The fossa is the sinuses. The blood temporal commonest site for this tends to gravitate to the temporal region but ex- type of haematoma. The haemorrhage arises from tends well beyond its limits. A thin capsule forms damage to the middle meningeal artery or its around the haematoma. In adults subacute hae- branches, severed diploic veins in the line of matomas are frequently bilateral; in early child- fracture, or sometimes from a torn transverse or hood they are almost always bilateral. The superior petrosal sinus. The haematoma is diagnosis is made when evidence of increased usually, but not always, associated with a fracture intracranial pressure and perhaps contralateral, of the temporal bone and there is nearly always an homolateral or bilateral pyramidal signs develop overlying visible scalp lesion. a few weeks after a head injury. In the absence of Brain-stem compression (vide supra) rapidly a history of trauma a clinical diagnosis of intra- develops, usually within 24 hours of the injury, cranial tumour is made and the haematoma re- and in about half the cases there is no improve- vealed by subsequent investigations. copyright. ment in the level of consciousness before the onset A chronic subdural haematoma reveals itself of brain-stem compression. In childhood an months or even years after a minor head injury initial period of coma seldom occurs; more often although again a history of trauma is often lacking. children are momentarily dazed and later become In most cases the clinical diagnosis is intracranial unconscious from the effects of the expanding tumour. The capsule tends to be thick; oc- haematoma. They sometimes have convulsions. casionally the whole of the haematoma becomes Also, wide separation of the sutures or fracture replaced by fibrous tissue and the presence of blood lines sometimes allows much of the blood to escape be the under the elastic some of pigment may only remaining evidence of

scalp producing degree trauma. http://pmj.bmj.com/ spontaneous decompression and delaying the onset In early childhood, birth trauma is thought to of compression of the brain. In infants, enough be a common cause of subdural haematoma. In blood may be lost from the circulation in the the majority of cases there is no characteristic formation of an extradural haematoma to cause clinical picture. Thus infants may show nothing severe anaemia and shock. more than restlessness and bad temper or there The mortality of extradural haematoma is still may be attacks of generalized convulsions, the about 50 per cent., for it is not sufficiently realized commonest manifestation of the condition in early that it is one of the most rapidly lethal conditions life. Sometimes vomiting occurs. There is on October 2, 2021 by guest. Protected in surgery. Immediate diagnostic burr-holes are pyrexia in more than half the cases and bulging indicated in traumatic coma if (a) the level of of the fontanelle in somewhat less than half. The consciousness does not rapidly improve, (b) the circumference of 2 level of consciousness declines, or new the head may be to 3 in. more abnormal (c) any than average. Retinal haemorrhages are quite neurological signs appear, e.g. hemi- common although papilloedema is rare owing to paresis, pupillary dilatation. the decompressive effect of separation of the sutures of the skull. The tendon reflexes may be Subdural Haematoma exaggerated but paresis of the limbs occurs in There are three varieties of haematoma ocur- only a small proportion of cases. The mani- ring between the dural and arachnoid membranes, festations in early life are thus vague. Therefore acute, subacute and chronic. An acute subdural a subacute or chronic subdural haematoma should haematoma is frequently found in head injuries be one of the conditions considered when a child but it is usually small and associated with severe is not thriving. Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from October 1959 OLIVER: Expanding Lesions of the Temporal Fossa 549 Subdural Hygroma or Hydroma homonymous upper quadrantic field defect, Subdural collections of colourless or yellow contralateral facial paresis sometimes associated fluid of raised protein content may occur with or with hemiparesis, and, when the abscess is on the without a history of head injury. Some follow dominant side, nominal dysphasia or aphasia may meningitis, especially that caused by H. influenzae. occur. If untreated, the abscess with its ac- They are frequently bilateral and although the companying cerebral oedema causes progressive temporal region is usually involved they tend to be brain-stem compression. widespread. The clinical manifestations are the same as those found with subdural haematomas Gliomas and long-standing collections are surrounded by a The commonest glioma encountered in the thin capsule. temporal lobe is the glioblastoma multiforme. It Intracerebral Haematoma is a very malignant tumour which, because of its rapid growth, its tendency to haemorrhagic in- The temporal lobe is the commonest site for a farction and the surrounding cerebral oedema, spontaneous intracerebral haematoma. Such a commonly causes acute effects as the result of haematoma may arise from rupture of an in- midbrain compression, and may be mistaken for a tracranial aneurysm or, less often, a vessel forming stroke. part of a vascular malformation. In either case there is commonly an associated subarachnoid haemorrhage. Often there is no discoverable Meningiomas cause for the occurrence of a spontaneous in- Medial sphenoid ridge meningiomas produce a tracerebral haematoma and in these cases sub- characteristic syndrome. Patients complain of arachnoid haemorrhage is exceptional. Rarely an unilateral loss of vision and sometimes unilateral intracerebral haematoma develops in an area of exophthalmos. There is homolateral optic softening caused by a previous head injury (late atrophy, diminished visual acuity, and, in the early post-traumatic apoplexy). An expanding hae- stages, a central scotoma. There may be papil- matoma in the temporal lobe usually causes very loedema on the other side. (Optic atrophy with acute brain-stem compression. central scotoma on one side and papilloedema copyright. on the other is known as the Foster-Kennedy Arachnoid Cyst syndrome.) When the optic tract is involved The outer wall of an arachnoid cyst is formed by instead of the optic nerve, there is an homonymous arachnoid and the inner wall by pia. It is an hemianopia. Ophthalmoplegia is present in the excessively rare type of congenital cyst which is majority of cases, and results from occlusion of the usually found between the frontal and temporal orbital fissure. The ophthalmic division of the lobes in the Sylvian fissure. It contains clear trigeminal nerve is affected in some cases; patients yellow fluid of greatly raised protein content. As then complain of 'pins and needles' over the forehead where there is diminished or absent the cyst occupies part of the temporal fossa it http://pmj.bmj.com/ tends to cause acute and sometimes fluctuating sensation. Temporal lobe epilepsy may occur, brain-stem compression. The importance of and is sometimes the presenting symptom. These arachnoid cysts is that their effects can be per- deeply placed tumours tend to envelop the internal manently relieved by excision of the outer carotid artery and to adhere to the optic nerve. arachnoid wall. Middle sphenoid ridge meningiomas usually grow to large dimensions before revealing them- Cerebral Abscess selves. Manifestations of raised intracranial pres- Abscesses occur more frequently in the temporal sure may be associated with personality changes on October 2, 2021 by guest. Protected lobe than elsewhere in the brain owing to the produced by involvement of the frontal and proximity of the middle ear and mastoid process. temporal lobes. Sometimes the presenting symp- A temporal lobe abscess is more likely to arise tom is unilateral exophthalmos (Figs. 2 and 3). from chronic infection of the middle ear than from Plain radiography may show hyperostosis or the original acute infection. A metastatic abscess, erosion of the lesser wing of the sphenoid. usually from infection in the lungs, may develop Occasionally the hyperostosis is widespread, in- anywhere in the brain including the temporal lobe. volving much of the orbit and middle fossa A cerebral abscess may also be caused by a pene- (Fig. 2). trating head injury. Most cerebral abscesses Lateral sphenoid ridge meningiomas produce mature in from one to two weeks and therefore few or no localizing signs. Those on the dominant there is usually time for localizing and lateralizing side may cause memory defects or nominal signs to be observed. A large abscess in the dysphasia. Radiography may reveal hyperostosis temporal lobe may produce a contralateral or erosion of bone. Upward angulation of the Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from 550 POSTGRADUATE MEDICAL JOURNAL October I959

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- E ... X - j :- - t -.;,. -~~~~~2,.js1- on October 2, 2021 by guest. Protected FI,. 3.-Proptosis of the right eve caused by the changes in the wall of the orbit shown in Fig. 2. middle cerebral artery may be seen in angiograms which is produced by thickening of the bony walls with meningiomas arising along the sphenoid ridge. of the orbit. Meningiomas en plaque are tumours which lie Sylvian fissure meningiomas. These tumours like a carpet over the dura mater, and are charac- are attached to the dura mater overlying the terized by an increase in thickness of the adjacent posterior ramus of the Sylvian fissure, and pene- bone and lack of neurological effects. The trate between the frontal and temporal lobes. tumour most often grows in relation to the Localizing evidence may be found, and includes sphenoid bone and runs a chronic course. The personality changes, contralateral facial paresis, presenting symptom is unilateral exophthalmos Jacksonian attacks beginning in the face, and Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from October 1959 OLIVER: Expanding Lesions of t.'e Temporal Fossa 551 nominal dysphasia with tumours on the dominant side. Investigations Lumbar Puncture This procedure should not be carried out in the presence of raised intracranial pressure due to an expanding lesion, for it may precipitate or aggra- vate brain-stem compression, sometimes with a fatal result. Furthermore, lumbar puncture is unlikely to yield worth-while information. Plain Radiography Fractures may be confirmed or revealed. In .. : t f i :: extradural haematoma, a fracture may be shown across the of the middle running markings *2...... meningeal vessels, although some extradural haematomas occur without a fracture. Bulging of the temporal fossa and/or elevation of the lesser wing of the sphenoid may be present Mi: with a long standing lesion, e.g. chronic subdural haematoma, chronic subdural hygroma, arachnoid cyst. If calcified, the pineal gland is usually seen to be displaced away from the side of a space-occupying lesion. In early childhood, the presence of raised in- FIG. 4.-Arteriogram showing the branches of the middle tracranial pressure is revealed by separation of the cerebral artery folded medially towards the midline copyright. sutures and convolutional by a subdural haematoma. There is also some dis- exaggerated markings placement of the anterior cerebral artery towards Increased width and tortuosity of vascular the channels, occasionally with enlargement of the opposite side. foramen spinosum, may be seen with meningiomas. Sometimes there are adventitious vascular channels In the A-P projection, subdural space-occupying converging towards the site of a meningioma. lesions show medial displacement of the vascular Increase in thickness of the lesser and greater tree on the side of the lesion, with the branches wings of the sphenoid, the roof and lateral wall of of the middle cerebral artery folded medially the occurs with most of the towards the main trunk, and there is an avascular orbit, meningiomas http://pmj.bmj.com/ lesser wing of the sphenoid and meningiomas en space lateral to the vessels (Fig. 4). plaque (Fig. 2). Rarefaction or total destruction Meningiomas of the sphenoid ridge tend to of the posterior clinoid processes may be caused produce localized and sharply angulated upward by long-standing raised intracranial pressure or displacement of the middle cerebral artery and its directly by the growth of adjacent meningiomas. branches. Meningiomas overlying the posterior Increased size and density of one posterior ramus of the Sylvian fissure produce the same type clinoid be seen with of of displacement as subdura ]lesions, but in some process may meningiomas cases the tumour the medial end of the lesser wing of the sphenoid. gives rise to a visible vascular on October 2, 2021 by guest. Protected Calcification can be demonstrated radiologically pattern. in some meningiomas, some astrocytomas and most Space-occupying lesions within the temporal oligodendrogliomas. lobe prtduce a characteristic upward curve of the whole (o the middle cerebral artery and its Carotid Angiography branches, best seen in lateral projections (Fig. 5). This is the most valuable investigation for the demonstration of space-occupying lesions in the Ventriculography temporal fossa. It is preferable to ventriculo- This investigation is avoided whenever possible graphy which dangerously increases intracranial in the diagnosis of expanding lesions in the pressure and aggravates or produces brain-stem temporal fossa for the reasons already given, compression. Angiography is seldom indicated to but may be required when lateralizing signs are demonstrate the presence of an extradural haema- not obtained or if angiography is unsatisfactory. toma, for the march of events is usually too rapid A-P views show displacement of the ventricles in this condition. towards the opposite side with angulation of the Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from 552 POSTGRADUATE MEDICAL JOURNAL October 1959

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FIG. 5.-Arteriogram showing the characteristic unfolding of the carotid copyright. 'syphon' and the upward curving of the middle cerebral artery produced by temporal tumours (in this case a glioblastoma multiforme). third ventricle on the septum lucidum (Fig. 6). LATERAL Lateral views taken after manoeuvres to fill the VENTRICLES I temporal horns may demonstrate absence of filling, deformity or displacement of the temporal horn. http://pmj.bmj.com/ Electroencephalography Because of the rapidity with which brain-stem TUMOUR compression is produced by some expanding lesions of the temporal fossa (e.g. extradural haematoma, intracerebral haematoma, some gliomas), there may not be time for this investigation THIRD VENTRICLES to be done. Subdural haematomas cause electrical on October 2, 2021 by guest. Protected ' silence' or waves of diminished potential over the compressed hemisphere. Meningiomas or I I intracerebral lesions change the normal alpha FIG. 6.-Drawing of ventriculograms (A-P views) rhythm (average io cycles per sec.) to delta showing the normal relationship of the third rhythm (average 2 cycles per sec.) in the vicinity ventricle to the septum lucidum on the left and the of the lesion. The the of the characteristic angulation of these structures pro- larger amplitude duced by tumours of the temporal lobe. (From waves, the larger is the mass of abnormally 'Basic Surgery' by kind permission of the pub- functioning brain; and the slower the rate of the lishers, H. K. Lewis, London.) waves the more acute is the lesion. Thus an intracerebral haematoma or abscess produces the Diagnostic Burr-holes most striking changes, the average glioma moderate When localization has been obtained by clinical changes, and slowly growing meningiomas minimal examination and appropriate radiological investiga- changes. tion, a burr-hole is made over the lesion. The Postgrad Med J: first published as 10.1136/pgmj.35.408.546 on 1 October 1959. Downloaded from October I959 OLIVER: Expanding Lesions of the Temporal Fossa 553 diagnosis of the various haematomas can be con- pus is aspirated through a brain cannula passed firmed or made by this means; pus from an through the diagnostic burr-hole. This may have abscess can be aspirated and an X-ray contrast to be repeated several times. After aspiration a medium injected; and small pieces of tumour can small volume of a solution of penicillin is injected be obtained for histological examination. into the abscess cavity. If this method of treat- Treatment ment fails, a bone flap is elevated and the capsule Extradural Haematoma of the abscess is removed. After the diagnosis has been established by Glioblastoma Multiforme means of a burr-hole, a temporal scalp flap is Many neurosurgeons do not operate on this elevated and the burr-hole is rapidly enlarged into tumour, if the diagnosis has been proven by biopsy, a temporal craniectomy with the aid of a double- for recurrence quickly occurs with or without action rongeur. The haematoma is quickly post-operative radiotherapy. Partial removal, evacuated and the bleeding, usually from the however, may be worth while for the relief of middle meningeal artery or its branches, is severe headache or to allow patients to put their arrested by diathermy coagulation. When oozing affairs in order. of blood occurs from the dura, it may be necessary to drain the extradural space for 24 hours through Meningiomas the posterior extremity of the scalp incision. These tumours are removed under induced Subdural Haematoma hypotension to minimize bleeding. The tumour is When the blood is in the fluid state, a rubber incised with a diathermy electrode and the bulk of catheter is passed through the diagnostic burr-hole its interior removed by means of a pituitary and incised dura mater, and the blood is washed rongeur or diathermy loop. The capsule of the out with isotonic saline. When large clots are tumour can then be retracted from the brain which present, a bone flap must be elevated and a flap of is thereby spared from injury during removal of the dura reflected to ensure adequate evacuation of the capsule. Removal of medial ridge meningiomas haematoma. may be dangerous because of their close relation- In children, as in adults, the ship to the internal carotid and middle cerebral haematoma is if possible washed out through a copyright. catheter, but it is always necessary to remove the arteries which are sometimes enveloped by capsule at a later date if impaired development tumour. After removal of a sphenoid ridge of the affected meningioma, its site of origin should be well hemispheres is to be avoided. coagulated by diathermy to reduce the risk of Subdural Hygroma recurrence. For the same reason, the dural A large proportion of the fluid escapes with a attachment of a Sylvian fissure meningioma must sudden gush when an opening is made in the dura be completely excised. Meningiomas en plaque mater (and capsule when present). The remainder extend like a carpet over the temporal fossa; is aspirated through a rubber catheter. In as their attachment is so extensive and as these if a is it must be removed children, capsule present tumours do not cause raised intracranial pressure, http://pmj.bmj.com/ on another occasion by craniotomy. no attempt is made to remove them. Moreover, Intracerebral Haematoma removal would not relieve the exophthalmos which Although it is often possible to relieve brain- is the presenting symptom. stem compression by aspiration of the fluid part of the haematoma through the diagnostic burr- Brain-stem Compression hole, it is usual to elevate a bone flap and evacuate The early recognition and relief of midbrain the clots. Sometimes a bleeding vessel or compression are often of great urgency if ir- aneurysm is discovered in the wall of the haema- reversible damage or death is to be avoided. The on October 2, 2021 by guest. Protected toma and can be occluded. only effective decompression is that obtained by cavity appropriate treatment of the causal lesion. There Arachnoid Cyst is no place for the classical subtemporal decom- The cyst is revealed when a diagnostic burr- pression in which the bone of the lateral wall of hole is made and the dura mater incised. Most of the temporal fossa is removed and the dura mater the yellow fluid escapes when the outer wall is widely opened. incised. A bone flap is elevated and the arachnoid Sometimes when the lesion has been correctly forming the outer wall of the cyst is removed. treated, midbrain compression persists. It is then The inner wall of the cyst, formed by the pia necessary to re-open the wound and ' reduce' the covering the adjacent part of the cerebrum, is left herniation of the uncus and hippocampal gyrus. undisturbed. During this procedure, care is taken not to damage Cerebral Abscess the posterior cerebral artery which prolapses with Appropriate antibiotics are administered. The the herniated brain.